The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Seats in transportation such as a vehicle include a seatback for supporting the back of a passenger, a seat cushion for supporting the lower body including the buttocks and thighs, and a head rest for supporting the back of the passenger's head, in which a recliner allowing for controlling an angle of the seatback with respect to the seat cushion is disposed at the joint of the seatback and the seat cushion.
In the recliners, there are a manual type in which a passenger adjusts the angle of a seatback using a lever and a power type in which a recliner is automatically operated by power from a motor that is operated by a switch. However, all recliners are desired to keep their parts strongly combined when they are operated regardless of the types to make passengers comfortable and secure safety against a collision.
That is, recliners include a part combined with a seatback and a part combined with a seat cushion, and these parts have to be firmly combined even when the recliners are operated. If they are not firmly combined, the seatback is easily changed in angle even by small shock, in which as the angle of the seatback is easily changed in a collision, so a passenger is injured.
As it is addressed to reduce the weight of a recliner that is a core part of a seat with the tendency of reducing the weight of a vehicle to improve the fuel efficiency, studies have been conducted to reduce the diameter and thickness of recliners.
We have discovered that when the diameter of a recliner is reduced, the diameter of the pitch circle of a rim gear that is one of important factors for the quality is also reduced. It adversely affects on the quality and strength. In addition, a method and a structure for clamping a lower part that is connected to the cushion frame of a seat and an upper part that is connected to a back frame have been developed, but it is desired to form many parts and thus manufacturing is difficult.
The description provided above as a related art of the present disclosure is just for helping understanding the background of the present disclosure and should not be construed as being included in the related art known by those skilled in the art.